A hoist or winch will function properly only if its cable is payed out and layed up evenly on its drum each time it is used. If tension on the cable is momentarily released, it will often unwind or tangle. Some prior art devices depend on the weight of a cable, the load on it, or the use of the frictional drag of a traction roller to overcome this problem. Others use a traction sheave driven by an independent power source.
When a cable is paid out without sufficient weight attached to its free end, it can also unwind from its drum too quickly and become tangled. Similarly, when a cable is layed up without sufficient tension at its free end, it may wind up too loosely. When a winch is used in a helicopter, for example, its load can come into sudden contact with the ground, thereby releasing the tension on the cable and causing it to tangle.
The present invention provides a means of controlling the cable of a winch or hoist to prevent it from tangling. By insuring that a suitable tension is placed on the cable at all times, whether it is being reeled in or payed out, all undesirable movement is prevented.
A feature of the present invention is the use of a drive gear train positively driven by the winch or hoist's drum through overrunning clutches which control a traction roller at all times.
Another feature of the present invention is its self-locking gear train which prevents the cable from becoming tangled while the drum is stationary.